Savings Interest
After-tax maturity amount
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About this tool
Choose an installment plan (monthly deposits) or a lump-sum deposit, enter the rate and term, and this calculator shows the after-tax amount you actually receive at maturity. It subtracts the 15.4% interest income tax by default, and a tax-free checkbox lets you skip that deduction for tax-advantaged products.
How to use
- Choose installment (monthly deposits) or deposit (lump sum).
- Enter the monthly deposit (or lump-sum amount) and the annual rate (%).
- Enter the term in months.
- Turn on tax-free if the product qualifies, then check interest before tax, the tax, and the amount at maturity.
Frequently asked questions
- How much interest income tax is deducted?
- The standard rate of 15.4% (14% income tax plus 1.4% local tax) is deducted from the interest. If the product is tax-advantaged, such as a tax-free comprehensive savings account, turn on the tax-free checkbox to skip the deduction.
- Why is installment interest less than principal times rate?
- Each monthly deposit only earns interest for the months remaining until maturity. The first deposit earns interest for the full term, but the last deposit earns almost none, so total interest ends up lower than "total deposited times rate."
- Does this use simple or compound interest?
- Simple interest. Actual bank products vary in how they compute interest (simple versus monthly compounding), so real results may differ slightly.
- Which is better, a deposit or an installment plan?
- At the same rate, a lump-sum deposit earns more interest because the full amount is invested from day one. An installment plan effectively earns interest on roughly half the principal on average, since deposits are spread out. If you do not have a lump sum, installment saving is the practical choice.
This is a simple calculation using simple interest. Actual results may differ based on how a bank computes interest (simple vs. monthly compounding), preferential rates, or changes to the tax rate.